Amusement devices of the shifting block type have been in widespread use for more than one hundred years. In one form of such puzzles, a series of rectangular tiles are confined closely packed, side by side in coplanar relation as a generally two dimensional or planar array by a housing frame which also provides a vacant tile admitting or parking space so as to permit sequential lateral coplanar movement of selected individual tiles within the frame in and out of the parking space to change the array, typically to reorder indicia forming a sequence of numbers or letters marked on the exposed surface of the tiles or to change a pattern or picture depicted by the tiles.
Examples of the very numerous puzzles of the type described above are taught by U.S. Pat. No. 1,101,567 issued to Ridgway in 1914; U.S. Pat. No. 4,422,641 issued to Collin in 1983; U.S. Pat. No. 4,548,410 issued to Morrone in 1985 and U.S. Pat. No. 5,267,723 issued to Bowen in 1993, and U.S. Pat. No. 5,785,318 issued 1998 to Nesis.
The structures of the prior sliding tile puzzles, constrain the tiles for translational sliding movement in coplanar relation along orthogonal axes so that indicia marked on the tiles is always positioned in a same direction which imposes an undesirably low limit on the number of different combinations of indicia and therefore the variety of patterns or pictures that can be obtained.